Propeller.



C. W. HOWELL, JR. PROPBLLBR.

APPLICATION FILED JULY 3, 1911.

1 1 1 9,826, Patented Dec. 8, 19 14.

THE NURRIS PETERS CO PHDI'O-L/THQ, WASHINGYON. D C

- enn STATllE PATENT OFFIUE. I

CHARLES WESLEYI IOWELL, 73.; 015 NEWARK; NEWJERSEY.

l PROPELLER.

To all whom it may concern: p

Be it known-that I, GHAnLss W'esLnY HOWELL, J12, a citizen of the United States,

My invention relates to improvements in propellers and more particularly, it has reference to aerial propellers having engaging surfaces whichwill act upon the air substantially throughout their area.

It is well known that a propeller draws air from the region before it and from the region surrounding its periphery and in so doing creates partial vacuums in these regions that are destroyed by atmospheric pressure seeking to maintain atmospheric equilibrium. The currents resulting from "such phenomena are welldefinedin character and it is obvious that a propeller having rotating and/forward movement will act upon these currents and give propulsive or.

tractive impulse, but it; has been observed that much of the air is forced beyond the surface of the ordinary and usual form of propeller blade before it is properly acted upon.

has been a slightly curved one and expe rience has shown that this surface does not act wholly upon the air but mostly at a distance from the cutting edge or toward the rear. It was early assumed that a broad blade surface would give the most efficient results. but recent practice has proven that a narrow blade is more efficient. the theory being that the narrow blade does not disturb the air unduly and cause a loss of efficiency. In the new form of blade surface presented herewith the cutting edge as ordinarily termed. has a negative angle. That is to say. the surface of the blade adjacent to the cutting edge is presented at an angle opposite to the angle of the blade as a whole and i is preferably curved in cross-section and so acts upon the atmospheric pressure current as to cause itto bend around the cutting edge and it is then drawn toward the engaging surface of the propeller blade by reason of the suction or vacuous condition caused by the recessed side of the cutting edge. It is obvious therefore that the atmospheric blades of the propeller.

The usual form of propeller blade surface Specification of Letters Patent. Patented Dec; 1914 Application filed July 3, 1911. Serial no. 636,763.

upon or to be acted upon quickly by the engaging surface of the blade near its forward edge therebyincreasing the efficiency of the pressure current is encouraged to act quickly blade due to the fact thatthe major portion of the engaging surface is aetuallybrought into useful service.

' In the accompanying drawings I have shown in Flgure 1 a planvlew of one form of propeller illustrating an application of my invention. Fig. 2 is an edge "iew of the same looking upwardly at Fig. 1, Fig. 3 is an enlarged plan view in dotted outline illustrating one blade of the propeller and showing cross sections of the same at five different points of the radius. and Fig. 4 is an end view lookingfrom left to right at Fig. 3. c c

Looking at Fig. 1. the upper left and the lower right edges. indicated by the reference characters 4 and 5. are the cutting edges of As shown in Fig. 2 these cutting edges are not horizontal as are the rear edges of the blades when the propeller is mounted upon. a vertical axis. It

will of course be understood that the cutting. edges may be made horizontal if desired but cutting edge and away from the engaglng Q The cross section of the blade. indicated 1 by the reference character 6 nearest the axis of the propeller has a curvature of small radius. the radius of the curvature of the next cross-section ind cated bv the reference character 74's slightlv greater. and the radius of the curvature of each of the other cross-sections 8, 9 and 10 is gre er as the tip of the blade is approached. This curvature at the cutting edge presents a negative angle th oughout the entire length of each blade. Thisnegativeanolemavbe mademore pronounced. and the width of the blade may be decreased, in the direction of the axis of the propeller. Under these cond tions. the atmospheric pressure current which is encountered more slowlv near the axis than near the periphery of the propeller, is nevertheless subiected to similar action. That is to say. after the atmospheric pressure current has rounded the modified negative angle of the cutting edge near the periphery with a cutting edge presenting a negative of the blade it is acted upon by the entire surface of a rapidly moving broad portion of the blade at a modified angle of incidence or curvature, While the atmospheric pressure current which has rounded the abrupt negative angle of the cutting edge near the axis of the bladeisbeing acted upon by the entire surface of a slowly moving narrow portion of the blade at an abrupt angle of incidence or curvature, thus equalizing conditions throughout the length of the blade.

The correct cross-section for the blade of the propeller is determined by the intended speed .of rotation of the propeller and the intended forward speed of the propeller while rotating. Inaddition to the negative angle along the cutting edge of the blade of the propeller it has also been found to be of advantage to form the end or tip of each blade with a negative angle graduated along a line equally distant at all points from the axis of the propeller as indicated by the reference characters 11 and 12. This causes the atmospheric pressure current from the region surrounding the propeller to recess itself within the negative angle at the tip of each blade after which it is caught upon the broad engaging surface of the blade be- Iore it escapes. Of course it will be understood that modi fications may be made without departing from the spirit of the invention as set forth in the claims.

I claim: 1. A propeller having ablade portion angle, said negativeangle becoming more abrupt in the direction of the axis of said propeller.

2. A propeller having a blade portion with a cutting edge presenting a negative angle becoming more abrupt in the direction of the axis of said propeller, said blade PQI'".

tion of curved cross section decreasing in radius in the direction of its axis.

3. A propeller having a blade portion with a cutting edge presenting a negative angle, and a tip also presenting a negative angle.

4:- A propeller having a blade portion with a cutting edge presenting a negative angle, said blade portion of curved cross section and presenting a negative angle at its tip.

5. A propeller having a blade portion with a cutting edge presenting a negative angle, and a tip also-presenting a negative angle, said tip being equally distant at all points from the axis of said propeller.

6. A propeller having a blade portion with a cutting edge presenting a negative 7 angle becoming more acute in the direction of the axis of said propeller, saidblade por- CHARLES WESLEY HOWELL, JR.

Witnesses:

EDWARD S. LYNCH, THOMAS A. Hun.

Copies of this patent may be obtained for five cents each. by addressing the Commissioner 01 Patents. Washington, D. G, 

